The subject matter disclosed herein relates to power management and distribution and, in one particular implementation, to power management in pump systems that operate at remote locations.
Extraction of natural resources (e.g., oil, natural gas, etc.) occurs in locations throughout the world. These locations are often found in remote regions, far from cities and towns and, likely, far removed from common sources of power, e.g., electrical power supplied by a power grid. Power is essential, however, to operate equipment (e.g., pumps) necessary to move resources from below the ground to pipelines and tanks for transport to other locales. At some sites, for example, pump systems inject chemicals (e.g., corrosion inhibitors) into wells to prevent pipeline corrosion, which can lead to leaks that discharge effluent at significant environmental and financial costs.
These pump systems make use of alternative power sources to operate pumps and other components in lieu of the electrical power supply via connection with the power grid. Although combustion-based devices (e.g., gas generators) may be used, preference is given to alternative energy sources (e.g., solar panels and wind turbines) to avoid fuel costs and hydrocarbon emissions. Some locations may also include storage devices to store energy from the alternative energy sources. The storage devices can supplement output from the alternative sources, e.g., during low-sun and/or low-wind conditions.
Batteries are one common type of storage device. Pump systems may utilize a number of batteries that form a system or an array. Examples of the array connect the batteries in parallel to meet the discharge and storage needs at each remote sight. However, batteries are known to discharge at slightly different rates. This characteristic can lead to voltage imbalances that impact the amount of current that is drawn from each battery found in the array. As a result, stronger batteries with charge levels that are relatively larger than the charge levels of weaker batteries in the array may tend to carry the weaker batteries when driving a load (e.g., the pump). Operation of the array in this manner can reduce the life-span of the batteries, which in turn will require maintenance at greater frequency to replace dead and/or under-performing batteries at the remote sight.
Solutions exist to avoid these discharge problems. The array may incorporate elements (e.g., diodes) to isolate common contact points. This solution can prevent stronger batteries from charging weaker batteries in the array. In other configurations, the array may include a DC/DC converter at each battery to maintain uniformity of the voltage levels at the common contact points. However, operation of the DC/DC converters and like devices draw power from the batteries, which reduces the total charge available to operate the pump system.